JPS6135412B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a liquid friction clutch, particularly for a cooling blower of an internal combustion engine, which has a clutch housing rotatable relative to the drive shaft, the clutch housing being separated by a partition from a storage chamber to a fluid friction clutch. a drive chamber having a drive wheel therein; the partition wall is provided with a hole which can be closed by a valve and interconnects the storage chamber and the drive chamber; The front side of the clutch has a DC-powered electromagnet disposed coaxially with the clutch in the storage chamber area, the clutch is glued to the electromagnet so that it can rotate relative to the electromagnet, and the excitation of the electromagnet is triggered by a signal from the thermoswitch. The present invention relates to a liquid friction clutch controlled by the above method.

In motor vehicle cooling systems, the fan speed is often adapted to the respective cooling requirement by the use of an adjustable clutch. A liquid friction clutch with filling control performance is used, and the liquid friction clutch consists of a housing rotatable with respect to a drive shaft, and the housing is divided by a partition into a storage chamber and a drive chamber having a drive wheel therein. It is convenient to do so. In the partitions of both chambers there are holes which can be closed by valves for adjusting the degree of filling of the clutch. In the structures used today,
Valve actuation takes place via a bimetallic or elongated material element located on the front side wall of the clutch. The transmission of this thermofiller deformation to the valve takes place via a piston or a so-called actuating pin.

Since the clutch with fan vanes is in the airflow past the engine cooler located in front of it, a thermo-filler in the clutch adjusts the actuation of the clutch based on the cold air temperature, which is a measure of the coolant temperature. control. Such a liquid friction clutch is
For example, it is described in German Patent No. 1284186.

Modern engine designs install a separate radiator for cooling the charge air, placing this radiator in front of the main water radiator.
Also, a ring cooler is used, which includes a radiator for the air-cooled engine and a fan installed in front of the blower. In all of these special designs, the simple liquid friction clutch described above is not applicable. The reason for this is due to the following facts. Because in the first case the cooling air is additionally heated by passing through the supercharged air radiator, and in the second case the air is heated only after passing through the fan. Therefore, the clutch must be configured to be controlled by the temperature of the engine coolant or engine parts, such that a control signal is generated by a suitable thermoswitch and transmitted to the clutch.

Compressed air, oil or electric current can be used as the signal transmission medium. However, the cost of compressed electricity and oil is significantly greater due to the need to install conduits and provide the necessary sealing and valving mechanisms. This type of pneumatic control is described in U.S. Patent No.
It is known from specification No. 3880265. Electrical signal transmission, on the other hand, is much cheaper.

In fan clutches, since it is often necessary to respond quickly to temperature changes, magnet control devices are provided which receive their signals via thermoswitches installed at critical locations on the structural parts to be cooled. Electrical control of a liquid friction clutch in conjunction with a magnet is described, for example, in German Patent Publication no.
It is known from the publication No. 1270399.

In this known arrangement, a baffle body which realizes emptying of the drive chamber is pulled out of the drive chamber by means of an electromagnet when the drive chamber is to be filled with oil. A ring-shaped magnet is fixedly arranged in front of the clutch. This requires a relatively large distance between the clutch and the magnet due to structural tolerances and vibrations. This has the disadvantage that the magnet must be dimensioned sufficiently large to move the buffling body against the required force of the return spring. This not only makes the magnet expensive and heavy, but also consumes significant power. This power consumption has a disadvantageous effect, especially since the clutch must be engaged when the current is interrupted for safe operation. As is well known, a motor vehicle fan clutch is only required for about 5% of the total driving time, so the electromagnet is receiving current for about 95% of the motor vehicle's operating time. Therefore, energy consumption is significant,
Efforts are being made to make do with as little magnetic force as possible.

The invention therefore seeks to create an electrically actuated magnet control which, by means of small electromagnets of low power and light weight, allows reliable adjustment of the fluid friction clutch described at the outset. Challenges and〓〓〓〓
do. Furthermore, for safe operation, the clutch should be connected in the event of a power supply failure. To achieve trouble-free operation and low maintenance costs,
It is also an object of the invention to avoid the provision of highly contaminated and expensive slip rings for powering the electromagnets. This slip ring is necessary for supplying power to the electromagnet when the electromagnet is installed in a rotating part.

This problem is achieved in a liquid friction clutch according to the invention of the type mentioned at the outset: a) a stationary electromagnet is mounted for relative rotation on the front side wall of the clutch of the clutch housing; b) the electromagnet is of opposite polarity to the energized electromagnet; a permanent magnet is disposed coaxially with the clutch on the valve lever supporting the valve; c. the minimum spacing between the electromagnet and the permanent magnet is determined by the abutment of the valve lever against the clutch housing or bulkhead; This is solved by becoming familiar with the problem.

According to the invention, an electromagnet, which is rotatably mounted relative to the clutch housing in the region of the storage chamber and is supplied with direct current, is attached to the valve lever controlling the oil circulation and has a permanent magnet of opposite polarity. Together, it is achieved that the repulsive action of both magnets brings the valve lever into the closed position when a current is applied, in which case the clutch is disconnected.
Upon removal of the current, the valve opens under the force of the compression spring, the clutch fills with oil and the blower reaches its maximum speed.

The combination of an electromagnet and a permanent magnet according to the invention allows a contactless force transmission to the valve lever rotating relative to the electromagnet, which greatly simplifies the control structure and improves operating safety. will improve.
By fixing the electromagnet so that it can rotate relative to the clutch housing, a slip ring is not required and the air gap between both magnets is kept very small, so that even relatively small magnetic field strengths can be used. This is sufficient and has an advantageous effect on the dimensions of the electromagnet and with it on the construction costs, bearing loads and power consumption. The opening distance of the valve lever is limited, for example, by its abutment on the clutch housing or on the bulkhead.

In order to avoid oil losses, it is advantageous to seal off the reservoir by means of a plate which has a thickness smaller than that of the electromagnet and is made of non-magnetizable material.

If tightness requirements are low, the seal can also be achieved by means of a sliding ring seal arranged between the rotating clutch housing and the stationary electromagnet in accordance with another embodiment of the invention.

Other features and advantages of the present invention will be explained in detail below with reference to drawings showing embodiments of the invention.

FIG. 1 shows an internal combustion engine 20 having a coolant circuit and utilizing a liquid friction clutch according to the present invention.
It is shown. The internal combustion engine 20 includes a cooling medium pipe 2
4 and 25, it is connected to the cooler 21 in an arbitrary manner. Behind the cooler and in front of the internal combustion engine there is represented a blower 22 connected to a liquid friction clutch according to the invention, which blower is driven by the crankshaft of the internal combustion engine 20 in a manner known per se. Ru. In the illustrated embodiment, a thermocouple 23 is arranged in the cooling medium return line 24, which is designed as an electric switch and which emits an electric signal for controlling the liquid friction clutch. Also shown in FIG. 1 is an electromagnet 7 used for the control of the liquid friction clutch, which electromagnet is in communication with a thermometer 23 via a power supply line 19, for example.

FIG. 2 shows a cross-section of an exemplary embodiment of a liquid friction clutch according to the invention on an enlarged scale compared to FIG.

The liquid friction clutch consists of a front clutch wall 1 to which, for example, fan blades 13 are fixed or formed integrally with the front clutch wall 1. The partition wall 2 divides the interior of the clutch with the back wall 12 into a storage chamber 2a and a drive chamber 10. Drive wheels 11 are arranged in the drive chamber 10 in a known manner. The partition wall 2 is the drive chamber 10
The oil supply hole 3 is opened and closed by a valve having a valve lever 4, for example. For actuation of the valve lever 4, which is mounted pivotably on a bearing 5, an electromagnet 7 with a coil 17 is used, which is supplied with direct current via a power supply line 8 and which is connected to the clutch in the region of the storage chamber 2a. The clutch housing is coaxially mounted with a bearing 9 so as to be relatively rotatable. According to the invention, the valve lever 4 is fitted with a permanent magnet 6, for example in the form of a disc, which is smaller than the electromagnet 7.
have opposite polarity. When electromagnet 7 is excited via thermofeeler 23, magnet 7 and magnet 6 repel each other. Since the electromagnet 7 is fixedly attached to the clutch housing, for example, by a strut 26, the valve lever 4 is pushed away by the repulsive force of the electromagnet 7 and closes the oil supply hole 3. The clutch is cut off. When the electromagnet 7 is deenergized, the valve is opened again by the force of the compression spring 18, the clutch is filled with oil and the blower reaches its maximum speed.

For the sealing of the storage chamber 2a with respect to the electromagnet 7, a plate 14 is arranged, which is made of a non-magnetizable material and has a thin wall thickness compared to the electromagnet 7, as the embodiment according to FIG. 3 shows. If tightness requirements are low, the sealing can also be effected by a sliding ring seal 1 arranged between the rotating clutch housing 1 and the fixed electromagnet 7 (FIG. 2).

The excitation of the electromagnet 7 is controlled by a thermofeeler 23 arranged in the cooling medium return pipe 24, as shown in FIG. The thermo-filler 23 can also be applied to the supply air or to the lubricating medium of the cylinder walls of the internal combustion engine, in which case the thermo-filler 23 can simply be connected to the respective machine part or to the fluid (supply air, cooling water, lubricating medium). Thermal contact is necessary.

When cutting off the current, the valve lever 4 is moved by the compression spring 1.
8, the oil supply hole in the bulkhead 2 is swung open, so that the clutch is engaged and the ventilator reaches its maximum speed.

Furthermore, in the embodiment shown in FIG.
The electromagnet 7 is designed to project into the storage chamber 2a and to be rotatably mounted on a bearing 9 in the front clutch wall 1.

The invention is not limited to the embodiments shown and described, but it is possible to choose to form the fluid friction clutch differently from the embodiments shown. It is important that the actuation of the valve for the oil supply hole 3 in the partition between the storage chamber and the drive chamber takes place by means of an electromagnet 7 which is in communication with the permanent magnet 6 and can be selectively excited.

The invention also covers all specialist modifications and developments of the features and measures described and/or illustrated, as well as subcombinations and subcombinations.

[Brief explanation of the drawing]

1 is a diagram of an internal combustion engine with a cooling and ventilation system, FIG. 2 is a cross-sectional diagram of an embodiment of a liquid friction clutch according to the invention, and FIG. 3 is a sealing plate between the electromagnet and the storage chamber. 2 shows a cross-sectional diagram of another embodiment having . 2... Bulkhead, 4... Valve lever, 6... Permanent magnet, 7...
Electromagnet, 14... Sealing plate, 16... Packing. 〓〓〓〓

Claims (1)

[Claims] 1. A liquid friction clutch, especially for a cooling blower of an internal combustion engine, having a clutch housing rotatable relative to the drive shaft, which clutch housing has a storage chamber and a drive wheel therein via a partition. a drive chamber with a drive chamber, and a hole is provided in the bulkhead, which can be closed by a valve and interconnects the storage chamber and the drive chamber, and the liquid friction clutch is arranged in the area of the storage chamber. In a liquid friction clutch having a DC-powered electromagnet disposed coaxially with the clutch, and in which the excitation of the electromagnet is controlled by a signal from a thermoswitch, a stationary electromagnet is capable of relative rotation to the clutch of the clutch housing. b) a permanent magnet of opposite polarity to the electromagnet under power is arranged coaxially with the clutch on the valve lever supporting said valve; c) the valve lever is attached to the clutch housing or bulkhead; A liquid friction clutch characterized in that a minimum distance between the electromagnet and the permanent magnet is determined by abutment against the electromagnet and the permanent magnet. 2. The liquid friction clutch according to claim 1, further comprising a sealing plate for sealing the storage chamber between the electromagnet and the permanent magnet. 3. A liquid friction clutch according to claim 1, characterized in that the electromagnet projects into the storage chamber and is provided with a seal for sealing against the outer periphery. 〓〓〓〓